This invention relates to an intramedullary catheter. More specifically, the present invention is directed toward an improved device and method for allowing repetitive delivery or withdrawal of fluids to or from the vascular system of bone marrow through a catheter device placed within a patient's bone.
Repetitive delivery of fluid into a patient's vascular system often entails an intravenous device. When a patient requires fluid during each of numerous treatment sessions, an intravenous device must be inserted into the patient's vein. Each time the device is inserted, the physician runs the risk of missing the vein and injecting fluid outside the vein. Moreover, physicians often find it difficult to find a vein, or once they do so, numerous injections into that vein may cause its rapid deterioration. In an effort to solve the above problems, numerous devices are commercially available which comprise a catheter commonly inserted into a large vein and having a self-sealing septum through which repetitive injections can be made into the catheter. Thus, instead of repetitively placing a needle into a vein, the needle can be repetitively placed through a septum and into a port attached to a conduit placed within the vein.
Intravenous catheters represent substantial improvements in the art, however, when used over a long period of time, they can cause infection and clotting in the vein near the area where the catheter is placed into the vein. Recently, a device and method were developed for repetitively placing fluid into the vascular system via bone marrow. Such a device incorporated herein as U.S. Pat. No. 4,772,261 comprises an intramedullary catheter placed into a tapped bore within the patient's bone and into the bone marrow. This device allows placement under the skin and the closing of the skin over the device such that the portion of the catheter extending outside the bone remains hidden under the skin. Although catheters placed into a patient's bone marrow represent improvements in the art, they are often difficult to place, and once in place, are difficult to find. It is important, when placing a bone catheter, that the head or outermost member of the catheter be large enough to be easily detectable (or palpable) by the physician so that he or she can target the injection needle into the septum of the catheter. Furthermore, it is important that once a catheter is in place, it be securely held within the bone marrow and will not cause pain during normal patient movement. It is also important that the catheter-bone interface be secure or tight enough so as not to leak fluid outside the bone and into the surrounding tissue. However, the base of the catheter must be designed or shaped not to cause necrosis of the underlying periosteum resulting in a nidus for infection. Still further, it is important that a device be provided for repetitive harvesting or withdrawing of fluid from bone marrow as well as repetitive delivery of fluid to bone marrow.